This disclosure concerns field-deployed water purification systems, especially for military use, disaster relief and other situations requiring a set of elements scaled for the particular application to be readily transported, set up and operated to produce purified potable water from unqualified sources. A configuration for such systems is disclosed wherein a demountable and re-mountable water pump is alternatively driven using a selected one of two or more alternative prime movers, such as a diesel engine or an electric motor, which prime movers are carried on respective different modular system elements. This configuration is beneficial for a system wherein the demountable pump is a heavy weight positive displacement high pressure pump that drives a reverse osmosis filtration unit.
As disclosed, for example, in U.S. Pat. Nos. 5,972,216 and 5,788,858, which are hereby incorporated by reference, it is known to deploy a modular water purification system having pump elements, filter elements, storage tanks and the like. The modular elements can be wholly or partly mounted on trucks or trailers, or can be discrete units that are carried as cargo to a site where needed to product potable water. Potable water might be obtained by purifying water from any of various sources, such as water from a natural watercourse such as a creek or river. Sea water is a source from which water can be desalinated by appropriate filtration techniques. Water also may be extracted and purified from sources that might have been considered acceptable but are contaminated or might be contaminated such as flooded municipal water supplies or swimming pools. Water also might be filtered because it originates in a source that might be exposed introduction of foreign materials such as pathogens by an attacker.
Water treatment in such situations comprises plural filtration steps. Solid material such as entrained silt and algae is separated by screening, settling, centrifugal motion, etc. Chemical fractions that may be in solution or entrained are absorbed, for example by chemical reaction producing a precipitate that is separated out or by exposure to a reactive surface at which the chemical fraction is immobilized. Water may be subjected to ion release materials such as copper, silver and other biocidal materials. The water can be passed through a reverse osmosis filter stage to remove ions, microbes and particles down to a very small size. The final product is chlorinated and may be dispensed or stored, for example in tanks or inflatable bladders from which the purified and chlorinated water is dispensed. Advantageously, these different filtration and treatment steps are accomplished by pumping water obtained from a source, through successive treatment steps that are accomplished at modular pumping filtration, treatment and storage modules.
The modules can be stages of processing in a self contained water treatment system, but a more versatile and readily serviceable system is provided by a system wherein the stages are substantially separated into discrete modular parts that can be used or not used when required, and coupled in different configurations for different purposes. For example, to serve capacity requirements, it may be necessary to provide conduits, pumps and filtration media defining parallel flowpaths to multiply the flow capacity that would be available with single flowpath. Different configurations and filtration steps may be appropriate for different needs. For example, treating muddy fresh water may require separation of particulates more than other steps. Treating clear sea water may require desalination more than particular separation. It is useful to provide modules with connections enabling different deployments and configurations.
Filtration media may be disposed in filter cartridges that are useful for some nominal flow volume that is a function of the characteristics of the raw water being treated, after which the cartridges need to be replaced. To accommodate different flow arrangements and to enable the elements at respective operating stages to be switched in and out, arranged in alternative flowpaths and generally configured for needs at the time, the above-cited U.S. Pat. Nos. 5,972,216 and 5,788,858 provide for modular arrangements wherein operating elements such as pumps, separators, tanks and filters are connected on site according to alternative operational requirements.
Filtration systems that employ reverse osmosis water purification elements, for example for desalination, have pumping pressure requirements that are generally higher than might be required simply to move water from a raw water source through a separator and into a tank. Initial raw water collection, solids screening and passing of the water through filtration media are done at relatively low water pressure. A pump that moves water through a reverse osmosis filter stage needs to apply a pressure differential across the reverse osmosis membrane that is sufficient to overcome the tendency of water to diffuse through the membrane toward the side with a greater ion density. For desalination, the pressure differential enables pure water to diffuse to the low pressure side, leaving the higher salinity brine behind on the high pressure side, to be flushed away. Assuming that a given flow rate is obtained by providing a predetermined membrane surface area, the flow rate can be increased by adding reverse osmosis filter stages in parallel.
The various alternative configurations are such that quick connect couplings are advantageous. Multiple pump modules that respectively operate at high or low pressure need to be available. High and low pressure conduits and fittings need to be organized. Appropriate manifolds and various valves are useful for switching and flowpath diversion as needed.
Field deployed potable water sources are more efficient than transporting purified water to a site of need whenever the need for water exceeds a short time. Field water purification units are useful for military force deployment, disaster relief and other situations in which a temporary need arises and municipal sources are not available. Water treatment facilities may be carried on trucks or trailers and used to fill tanks carried on trucks or trailers, but so long as the facilities are needed at a certain location, mobility is not a requirement. Field deployment can be provided using modular elements packaged to be transported to a site and dropped off. The modular elements are sized to weight specifications enabling manipulation of the elements by a few soldiers or other workers. For example, if an assembled set of water treatment modules are dropped near a raw water source, and no single module weighs more than about 200 lbs. (about hundred kilograms), two soldiers working together can configure a water treatment plant on the same day, producing potable water sufficient to serve a company of soldiers.
A water treatment system divided into relatively small elements has the potential benefit that each discrete element can be made light in weight and is easier to handle or requires fewer people than a heavier element. If there are numerous modules that can be mixed and matched and coupled in different ways, the water treatment system may be more versatile, but configuring and connecting the modular parts is complex. It would be beneficial to maximize versatility, minimize individual module weight and to make the configuration and connection of an operable system uncomplicated.
The present disclosure addresses the nature and configuration of power sources used to operate the water purification system, i.e., the water pumps. Suction and pressure lines are required to draw in raw water, to establish a pressure differential across filter media, and to provide a head of pressure and/or to lift the elevation of water to be dispensed. The necessary pumps can be driven by electric motors if there is a source of electric power, which is advantageously quiet. Pumps can be driven directly by internal combustion engines. Pumps can be driven by electric motors that are powered from a generator driven from an internal combustion engine. These and other configurations are possible.
For military applications, an internal combustion engine may be desirable so as to operate independently, but an electric motor is lighter, quieter and relatively maintenance free if a source of electric power is available. Some military vehicles provide for electric power take off from a generator coupled to the vehicle power plant. It is an aspect of the present disclosure to provide the capability of using either or both of electric motors and internal combustion engines in a modular water purification system, and to do so in a way that minimizes the weight of the modular components while at the same time reducing the complexity required to couple and decouple certain water pumps.